The disclosure relates generally to a method and apparatus for power-up detection for an electrical monitoring circuit which, in one application, may be used to prevent unauthorized access to chip contents.
Many complex processors such as those including systems on a chip (“SoC”) and used in video game consoles, store digital media content that is copyrighted or other proprietary information that needs to be secure. Such data is typically stored and transmitted in an encrypted format. Unfortunately, hackers sometimes purchase consoles with the goal of identifying the encryption keys used to protect the contents of the chip. With the encryption keys identified, the hacker can decrypt the content and exploit it in a variety of ways.
One method hackers use to gain access to the encryption keys is to change the operating parameters of the chip to place it in an undesirable mode of operation. When in such an undesirable mode, the chip's standard security circuits may be non-functional, thereby permitting access to the encryption keys, and then the proprietary content. For example, if a chip is forced to operate under very high or very low ambient temperatures, the chip may operate in an undesirable mode. Similarly, if any of a variety of voltage inputs to the chip are increased or decreased beyond certain limits, the chip may operate in an undesirable mode. Finally, if the clock input to the chip is modified in period or low time, the chip may operate in an undesirable mode. If the malfunctions resulting from an undesirable operating mode are repeatable, it is possible stored media content or other information can be hacked.
Moreover, processors may be particularly vulnerable to such hacking during transitional modes of operation such as power up and reset. Some processors have a platform security processor (“PSP”) or security functional block which is configured to place the processor into a secure operating mode when a hacking attempt is detected, but this is often not sufficient as such a security processor is limited to this secure operating mode and not during such transitional modes.
Accordingly, there exists a need for an improved method and apparatus for maintaining the chip in a reset mode during power-up until it is determined that certain voltages have reached safe levels to thereby prevent unauthorized access to the contents of the chip and address one or more of the above-noted drawbacks.